Cement mixer trucks are used to transport loads of mixed, non-hardened cement. These trucks typically have a rotatable mixing drum for storing the cement mixture and a hydraulic system and mixing drum controller for controlling the rotation of the drum. The agitation caused by rotating the mixing drum prevents the cement mixture from setting up and hardening. Therefore, the mixing drum is typically rotating both when the truck is moving and when the truck is stopped.
As a result of the mixing drum rotating, the position of the cement mixture in the drum is generally shifted in the direction of rotation, both laterally and upward along the inside of the drum. This shift of the cement load results in a shift of the center of gravity of the truck, which makes one side of the vehicle heavier that the other side. The uneven loading of the vehicle can have a detrimental effect on vehicle performance. For example, when the vehicle is moving, the offset of the center of gravity increases the rollover risk of the vehicle in the direction of the heavier side. Lateral (side) acceleration creates a force at the center of gravity, “pushing” the truck horizontally. The friction between the tires and the road opposes that force. If the lateral force is high enough, one side of the truck may begin to lift off the ground potentially causing the vehicle to roll over. Thus, the height and lateral offset of the center of gravity affect roll stability.
In addition, uneven distribution of weight across the wheels of the vehicle can adversely impact performance of the vehicle in other ways, such as braking and traction control. For example, in an antilock braking system (ABS), an evenly distributed load allows each wheel to more optimally brake. Furthermore, with automatic traction control (ATC) systems, uneven loading may cause a drive wheel to slip.